Time validation indicator

ABSTRACT

A time validation indicator is disclosed comprising at least a receiving layer and an activating layer. The receiving layer comprises at least one or more masking colorants and one or more deactivators that cause and maintain the one or more masking colorants in an initial colored state. The activating layer comprises at least one or more migratory activators that migrate into the receiving layer upon at least a portion of the receiving layer being placed in contact with at least a portion of the activating layer to initiate a predetermined time period. The migration of the one or more migratory activators into the receiving layer causes at least a portion of the one or more masking colorants to advance to a final colorless state resulting in a visual color change of the receiving layer that indicates the predetermined time period has elapsed. Also disclosed are methods for creating and using the inventive time validation indicator.

BACKGROUND OF THE INVENTION

These teachings relate generally to time validation indicators, and moreparticularly, to the preparation and use of time validation indicatorsthat are easily adaptable for various time intervals of expiration, andhence capable of providing digital and distinct indication of expirationof a predetermined time period.

Various indicators have been utilized in a number of differentapplications for indicating when a specific time period has elapsed. Forexample, time-temperature indicators have been used in areas such aspharmaceutical and food industries for indicating when perishablematerials, i.e. materials having a measurable shelf-life, reach apredetermined expiration date and need to be discarded. Other examplesof areas for which time indicators have been utilized include generalinventory management, monitoring projects and activities, securitybadges, and a host of other time dependent events.

Currently, the majority of known time indicators provide, afteractivation, a visual indication of a predetermined period of time. Manyof these known time indicators provide this visual indication by way ofcolor change through the use of dye migration or dye diffusion. Forexample, U.S. Pat. Nos. 4,903,254, 5,822,280, and 7,139,226 employ theuse of colored indicators that migrate, once activated, through opaquefilms to indicate the passage of time. In these systems, the finalcolored state of the indicator is generated in or below the opaque layerand then migrates through this layer to become visible. Alternativeefforts, such as those cited U.S. Pat. Nos. 4,212,153, 4,248,597, and4,643,122 describe similar approaches that include the migration of anacid/base or solvent within a laminated structure containing a pHindicator, such that a color change results following activation due toa subsequent change in pH. Other known time indicators provide a colorchange by way of chemical reactions, such as those cited in U.S. Pat.Nos. 3,018,611 and 4,812,053 which employ an oxygen reactive materialthat reacts with oxygen upon exposure and produces a visual colorchange. Furthermore, U.S. Pat. No. 5,085,802 describes an additionalcolor change reaction suitable for providing a visual indication of apredetermined period of time. This color change reaction involves thegeneration of an acid/base “in-situ” through the use of enzymes in thepresence of a pH indicator, thereby producing a subsequent color changewith a change in pH.

A general problem that exists with approaches based on dye migration ordye diffusion, as well as chemical reactions, to provide a visualindication of a predetermined time period is the gradual nature of thecolor change over the time period, thereby making it difficult for theuser to ascertain exactly when the designated end point is reached. Acommon approach in addressing the foregoing problem is by additionallyincorporating the use of a control color strip or target strip adjacentto the time indicator in order to make visual comparisons as timeprogresses. However, the use of color or target strips add to the costof making and employing the time indicators, as well as still having thepossibility of user error in determining when the predetermined timeperiod has elapsed. Time indicators that rely solely on the migration ofdyes, solvents, reactants, etc cannot escape the grey scale problemsince it is an inherent aspect of diffusion kinetics. Another drawbackincludes the inability to use such time indicators for long timeperiods, i.e. month(s) or year(s). Therefore, there is a continued needto develop reliable, visual time indicator systems and devices which canbe used for a variety of different applications and predetermined timeperiods.

There have been further attempts in providing a visual indication of apredetermined period of time with the migration of jelly or liquidsthrough a wick material to indicate the lapse or elapse of time, such asthose cited in U.S. Pat. Nos. 3,954,011 and 3,962,920. Thesetechnologies impregnate the wicking material with an indicator and theprogress of a fluid along the wick material is visibly indicated andused to measure or determine a lapse or elapse of time. One drawback tosuch approaches is that they generally require a reservoir of fluid thatis needed in order to visually indicate or measure a passage of time.Such a requirement increases the cost of utilizing these types ofapproaches, as well as limits their applicability, etc.

Given the drawbacks of the current time indicators utilized to provide avisual indicator of a predetermined period of time, there is, therefore,a need for a time validation indicator that is capable of providing adigital (step-wise) and distinct indication when a predetermined timeperiod has elapsed. In providing a digital and distinct indication, sucha time validation indicator affords a more reliable and accurate visualindication than that of the prior art. It is also desirable, therefore,to provide a time validation indicator that is easily adaptable for usein determining expiration of a wide variety of time intervals, i.e.short or longer periods of time, resulting in more applicability.Furthermore, it also desirable to provide a time validation indicatorthat is inexpensive and simpler to construct and to employ than that ofthe prior art.

BRIEF SUMMARY OF THE INVENTION

The present teachings provide for a time validation indicator comprisinga receiving layer and an activating layer. The receiving layer comprisesone or more masking colorants and one or more deactivators that causeand maintain the one or more masking colorants in an initial coloredstate. In some instances, the receiving layer may further comprise oneor more polymers that function together with the one or moredeactivators to cause and maintain the one or more masking colorants tobe in the initial colored state. The activating layer comprises one ormore migratory activators that migrate into the receiving layer upon atleast a portion of the receiving layer being placed in contact with atleast a portion of the activating layer to initiate a predetermined timeperiod. The migration of the one or more migratory activators into thereceiving layer causes at least a portion of the one or more maskingcolorants to advance to a final colorless state resulting in a visualcolor change of the receiving layer that indicates the predeterminedtime period has elapsed. In some instances, the one or more maskingcolorants may be one or more leuco dyes. In other instances, the one ormore deactivators may be one or more electron accepting compounds. Infurther instances, the one or more migratory activators may be one ormore polyoxygenated compounds. In certain constructions, at least one ofthe receiving layer or the activating layer may further comprise one ormore plasticizers that aid in the migration of the one or more migratoryactivators into the receiving layer. In other constructions, at leastone of the receiving layer or the activating layer may also comprise atleast one of one or more dispersants, one or more thickeners, one ormore wetting agents, or one or more defoamers. In other aspects, atleast one of the receiving layer or the activating layer may furthercomprise one or more adhesive materials that bond together at least aportion of the receiving layer to at least a portion of the activatinglayer when placed in contact. In further instances, at least one of theactivating layer or the receiving layer may also comprise one or morestatic colorants that are capable of being visually observed upon atleast a portion of the one or more masking colorants of the receivinglayer being partially or fully in the final colorless state. The timevalidation indicator of the present teachings may additionally comprisean adhesive layer that bonds together at least a portion of thereceiving layer to at least a portion of the activating layer whenplaced in contact. The time validation indicator of the presentteachings may also comprise a colorant layer that comprises one or morestatic colorants that are capable of being visually observed upon atleast a portion of the one or more masking colorants of the receivinglayer being partially or fully in the final colorless state. The timevalidation indicator of the present teachings may further comprise atiming layer that at least partially retards the rate of migration ofthe one or more migratory activators into the receiving layer. The timevalidation indicator of the present teachings may optionally compriseone or more base substrates. In some instances, one of the one or morebase substrates may include an indicia area that is capable of beingvisually observed upon at least a portion of the one or more maskingcolorants of the receiving layer being partially or fully in the finalcolorless state.

The present teachings also provide for a method for fabricating a timevalidation indicator. The method of the present teachings comprisesforming a receiving layer that comprises one or more masking colorantsand one or more deactivators that cause and maintain the one or moremasking colorants to be in an initial colored state. In some instances,the receiving layer may further comprise one or more polymers thatfunction together with the one or more deactivators to cause andmaintain the one or more masking colorants to be in the initial coloredstate. The method of the present teachings further comprises forming anactivating layer that comprises one or more migratory activators thatmigrate into the receiving layer upon at least a portion of thereceiving layer being placed in contact with at least a portion of theactivating layer to initiate a predetermined time period. The method ofthe present teachings further comprises placing at least a portion ofthe receiving layer in contact with at least a portion of the activatinglayer to initiate the predetermined time period and the migration of theone or more migratory activators into the receiving layer. The migrationof the one or more migratory activators into the receiving layer causesat least a portion of the one or more masking colorants to advance to afinal colorless state resulting in a visual color change of thereceiving layer that indicates the predetermined time period haselapsed. In other instances, at least one of the activating layer or thereceiving layer may further comprise one or more static colorants thatare capable of being visually observed upon at least a portion of theone or more masking colorants of the receiving layer being partially orfully in the final colorless state. The method of the present teachingsmay further comprise applying an adhesive means that bonds together atleast a portion of the receiving layer to at least a portion of theactivating layer when placed in contact. The applying of the adhesivemeans may include rendering an adhesive layer onto at least a portion ofat least one of the receiving layer or the activating layer.Alternatively, or in addition, applying the adhesive means may compriseincorporating one or more adhesive materials into at least one of thereceiving layer or the activating layer. The method of the presentteachings may also include rendering a colorant layer disposed onto atleast a portion of the activating layer, in which the colorant layercomprises one or more static colorants that are capable of beingvisually observed upon at least a portion of the one or more maskingcolorants of the receiving layer being partially or fully in the finalcolorless state. The method of the present teachings, may furthercomprise rendering a colorant layer disposed onto at least a portion ofthe receiving layer, in which the colorant layer comprises one or morestatic colorants that are capable of being visually observed upon atleast a portion of the one or more masking colorants of the receivinglayer being partially or fully in the final colorless state. In someinstances, the method of the present teachings may also compriseapplying a timing layer disposed onto at least a portion of theactivating layer or, in the alternative, disposed onto at least aportion of the receiving layer. The timing layer at least partiallyretards the rate of migration of the one or more migratory activatorsinto the receiving layer. The method of the present teachings mayadditionally comprise rendering one or more base substrates, in which atleast a portion of at least one of the activating layer or receivinglayer is disposed onto the one or more base substrates. In someinstances, one of the one or more base substrates may include an indiciaarea that is capable of being visually observed upon at least a portionof the one or more masking colorants of the receiving layer beingpartially or fully in the final colorless state.

The present teachings further provide for a method for indicating apredetermined time period has elapsed. The method of the presentteachings comprises providing a time validation indicator that comprisesa receiving layer and an activating layer. The receiving layer comprisesone or more masking colorants and one or more deactivators that causeand maintain the one or more masking colorants to be in an initialcolored state. The receiving layer may further comprise one or morepolymers that function together with the one or more deactivators tocause and maintain the one or more masking colorants to be in theinitial colored state. The activating layer comprises one or moremigratory activators that migrate into the receiving layer to cause atleast a portion of the one or more masking colorants to advance to afinal colorless state that results in a visual color change of thereceiving layer. In some aspects, at least one of the activating layeror the receiving layer may further comprise one or more static colorantsthat are capable of being visually observed upon at least a portion ofthe one or more masking colorants of the receiving layer being partiallyor fully in the final colorless state. The time validation indicator mayfurther comprise an adhesive means that bonds together at least aportion of the receiving layer with at least a portion of the activatinglayer when placed in contact. The time validation indicator may alsocomprise a colorant layer having one or more static colorants that arecapable of being visually observed upon at least a portion of the one ormore masking colorants of the receiving layer being partially or fullyin the final colorless state. The time validation indicator mayoptionally comprise a timing layer that at least partially retards therate of migration of the one or more migratory activators into thereceiving layer. The time validation indicator may also comprise one ormore base substrates. In some instances, one of the one or more basesubstrates may include an indicia area that is capable of being visuallyobserved upon at least a portion of the one or more masking colorants ofthe receiving layer being partially or fully in the final colorlessstate. The method of the present teachings further comprises placing atleast a portion of the receiving layer in contact with at least aportion of the activating layer to initiate the predetermined timeperiod and the migration of the one or more migratory activators intothe receiving layer. The method of the present teachings furthercomprises detecting the visual color change of the receiving layer thatindicates the predetermined time period has elapsed. The method of thepresent teachings may also comprise applying the time validationindicator to at least a portion of a surface of an object.

BRIEF DESCRIPTION OF THE DRAWINGS

The present teachings are illustratively shown and described inreference to the accompany drawings, in which

FIG. 1 is a schematic drawing of a time validation indicator accordingto one aspect of these teachings;

FIG. 2 is an example of a chemical structure and mechanism of colorationof the one or more masking colorants in the instance where the one ormore masking colorants are a type of fluoran dye;

FIG. 3 is an example of a chemical structure and mechanism of colorationof the one or more masking colorants in the instance where the one ormore masking colorants are a type of phthalide dye;

FIG. 4 is a schematic drawing of a time validation indicator accordingto a second aspect of these teachings;

FIG. 5 is a schematic drawing of a time validation indicator accordingto another aspect of these teachings;

FIG. 6 is a schematic drawing of a time validation indicator accordingto a further aspect of these teachings;

FIG. 7 is a schematic drawing of a time validation indicator accordingto another aspect of these teachings;

FIG. 8 is a graph illustrating the affect different concentrations ofone or more deactivators have on the timing period of the presentinvention;

FIG. 9 is a graph illustrating the affect different concentrations ofone or more migratory activators have on the timing period of thepresent invention;

FIG. 10 is a graph illustrating the affect various types of one or moremigratory activators have on the timing period of the present invention;

FIG. 11 is a graph illustrating the affect different concentrations ofone or more plasticizers within the activating layer have on the timingperiod of the present invention; and

FIG. 12 is a graph illustrating the affect different concentrations ofone or more plasticizers within the receiving layer and activating layerhave on the timing period of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present teachings are directed to the creation and use of timevalidation indicators that can provide a digital and distinct visualindication of expiration of a predetermined time period with the use ofat least a receiving layer and an activating layer that, when placed incontact with each other to initiate the predetermined time period,produce a visual color change indicating the predetermined time periodhas elapsed.

For a better understanding of the disclosure, the following terms areherein defined:

A “liquid carrier medium” is a liquid that acts as a carrier formaterial(s) distributed in a solid state and/or substantially dissolvedtherein.

As used herein, a “formulation” is a liquid carrier medium, as definedabove, comprising one or more polymers either dissolved in and/ordistributed in a solid state within the liquid carrier medium. Theformulation may additionally comprise one or more materials that aredistributed in a solid state and/or substantially dissolved therein.

A “layer” as used herein refers to a film resulting from the applicationand substantial drying of a formulation, or in some instances by way ofextrusion, injection molding, etc.

The following disclosure describes time validation indicators, as wellas the methods and materials for creating such indicators. Theseindicators possess a number of superior qualities, such as ability toprovide digital and distinct indication of a predetermined time period,as well as allow for easy manipulation of the timing period such thatthese indicators can be utilized for various predetermined time periods,e.g. short, i.e. hour(s), day(s), or week(s), or long, i.e. month(s) oryear(s).

Generally speaking, the time validation indicator, according to thepresent teachings, employs the use of at least a receiving layer thatcomprises one or more masking colorants and one or more deactivators,and an activating layer that comprises one or more migratory activatorsthat migrate into the receiving layer upon at least a portion of thereceiving layer being placed in contact with at least a portion of theactivating layer to initiate the predetermined time period. Thismigration of the one or more migratory activators causes a visual colorchange of the receiving layer, thereby indicating the predetermined timeperiod has elapsed. It should be noted, that the orientation or orderingof the layers of the time validation indicator is not limited by theschematic drawings which are generally presented herein and forillustrative purposes only. More specifically, the top most layer of thetime validation indicator that is viewed by the end user to observe thevisual color change may in some instances be that of the activatinglayer, whereas in other instances may be that of the receiving layer.

Turning now to FIG. 1, is a schematic illustration of one aspect of thetime validation indicator, according to the present teachings. In thisexample, the time validation indicator (2) comprises a receiving layer(4) and an activating layer (6). The receiving layer (4) comprises oneor more masking colorants and one or more deactivators in which the oneor more deactivators cause and maintain the one or more maskingcolorants in an initial colored state, prior to the initiation of thepredetermined time period. The activating layer (6) comprises one ormore migratory activators which migrate into the receiving layer (4)when at least a portion of the receiving layer (4) is placed in contactwith at least a portion of the activating layer (6). Once the receivinglayer (4) and activating layer (6) are placed in contact, thepredetermined time period and the migration of the one or more migratoryactivators into that of the receiving layer (4) are initiated, therebycausing at least a portion of the one or more masking colorants to beginto advance to a final colorless state. As the one or more maskingcolorants advance to the final colorless state over the predeterminedtime period, a visual color change of the receiving layer (4) occurs.Once at least a portion of the one or more masking colorants reach thefinal colorless state, the resulting visual color change of thereceiving layer (4) indicates that the predetermined time period haselapsed.

Prior to the activation of the time validation indicator, i.e. prior toplacing at least a portion of the receiving layer in contact with atleast a portion of the activating layer to begin the predetermined timeperiod, the one or more masking colorants in the receiving layer are inan initial colored state by way of the presence of the one or moredeactivators. The one or more deactivators, e.g. electron-acceptingcompounds such as, for example, Lewis acids, clays, or proton-donatingcompounds, cause and maintain, prior to activation, the one or moremasking colorants to be an initial colored state by interacting,chemically or physically, with that of the one or more masking colorantswithin the receiving layer. In some instances, the receiving layer mayfurther comprise additional one or more polymers that function togetherwith the one or more deactivators to aid in causing and maintaining theone or more masking colorants to be in the initial colored state. Insuch instances, these additional one or more polymers along with thepolymer(s) of the receiving layer may be the same, or in the alternativethe one or more polymers may be different than that of the polymer(s) ofthe receiving layer.

Various colorants may be used as the one or more masking colorantswithin the receiving layer of the present invention, e.g. dyes. Suitabledyes include, but are not limited to, leuco dyes which are capable ofreversibly forming a colored, carbonium ion species such as thosedepicted in FIGS. 2 and 3. Examples of suitable leuco dyes include, butare not limited to, spiropyrans, benzopyrans, fluoran dyes such as2′-anilino-3′-methyl-6′-(dibutylamino) fluoran, illustrated in FIG. 2,phthalide dyes such as crystal violet lactone, illustrated in FIG. 3,triarylmethane phthalides, diarylmethane phthalides, or monoheterocyclicsubstituted phthalides, or those or similar to those described in U.S.patent application Ser. No. 13/178,766, which is incorporated byreference herein in its entirety. It should be noted that the foregoingchromogenic compounds are given for purposes of illustration since anychromogenic compound which is capable of interacting with electronaccepting compound(s) may be employed as the one or more maskingcolorants of the receiving layer. Given that the human eye cannotdiscriminate optical density changes that occur at high initial density,having, prior to activation of the time validation indicator, the one ormore masking colorants in an initial colored state and upon activation,advance to a final colorless state allows for the time validationindicator to provide a more digital color change. This is because theoptical density of the receiving layer has to be lowered significantlybefore the color change of such layer can be perceived. As a result,such an approach, i.e. having the one or more masking colorants advancefrom an initial colored state to a final colorless state, is contrary tothe general approach utilized in prior time indicators.

In the instances where the one or more masking colorants are one or moreleuco dyes, it is generally believed that the color forming reaction ofthe leuco dye(s) occur through the interaction of the electron donatingcolorless leuco dye(s) with one or more electron accepting compound(s)to produce the reversible opening of the lactone ring(s), see e.g. FIGS.2 and 3, yielding the resonance-stabilized cationic leuco dye(s) in theinitial colored state. The properties of the color development system,i.e. the one or more leuco dyes and one or more electron-acceptingcompounds, are a complex subject of investigation and it has becomeobvious that many parameters can influence the kinetics of the ringopening reaction of the leuco dye(s).

As described in more detail below, a large number of environmentalfactors can influence whether the one or more leuco dyes, when utilized,are in the opened colored form or the closed colorless form. As aresult, this provides great flexibility in adjusting the time validationindicator of the present teachings by way of manipulating theformulation of both the receiving layer and/or the activating layer.

Although not intended to be bound by theory it is believed that in theinstance where the one or more masking colorants are that of one or moreleuco dyes and the one or more deactivators are one or more electronaccepting compounds, the one or more deactivators function as complexingagents or hydrogen bonding agents with the opened form of the leucodye(s) to generate a conjugated system. The class of leuco dyes that arerepresented by photochromic dyes such as, the spirooxazines, have beenwell studied and certain aspects of their characteristics can be relatedto the leuco fluoran and phthalide lactone type dyes useful in thepresent invention. Specifically, the environmental conditions thatinfluence the transformation from colorless to colored via opening ofthe lactone ring appear to be similar for both classes of lactone typedyes. Like the Spirooxazines, the triarylmethane and fluoran leuco dyesare comprised of two aromatic nearly planar moieties. These moieties arelinked by a tetrahedral sp³ spiro-carbon which insulates the twoπ-electron systems from conjugation. Due to the lack of conjugation, thespiro type compounds are pale yellow or colorless. However, conditionswhich favor ring opening and conversion of the spiro compound to a sp²hybridization result in the aromatic groups aligning its π-orbitals witheach other and forming a conjugated system which is now able to absorbvisible light, becoming a highly colored cationic species, see e.g.FIGS. 2 and 3.

Spirooxazines have also been studied in different types of polymers,e.g. cellulose acetate butyrate, polyurethanes, PVC, epoxies, acrylics,polyester, etc., in an attempt to modify their sensitivity to ringopening. These studies show that the ring opening reaction is highlysensitive to the viscosity of their medium. For example, the lowering ofthe glass transition temperature (Tg) of the host matrix will improvethe ease of the transition from colorless to colored and the reverse.The viscosity of the surrounding matrix has a large effect on theopening of the ring system of the one or more leuco dyes because of thesize of the fragments that must rotate relative to each other to achievethe sp² state. This was elegantly demonstrated in “The GenericEnhancement of Photochromic Dye Switching Speeds in a Rigid PolymerMatrix,” by R. A. Evans et. al., Nature Materials, Vol. 4 (2005), pp.249-253, in which covalent photochromic-oligomer conjugates were createdand consisting of a leuco dye and a soft, low-Tg oligomer such as,poly(dimethylsiloxane) or poly(ethyleneglycol), to protect the leuco dyefrom a harsh switching environment, i.e. from a rigid or high-Tgpolymer. The leuco dye is protected by the spontaneous coiling of itsattached low-viscosity oligomer, which insulates the leuco dye from thesurrounding high-Tg, high-viscosity bulk matrix, as described anddisclosed in U.S. Pat. No. 7,807,075 which is incorporated by referenceherein in its entirety. The leuco dye can be thought of as beingpermanently lubricated and protected at the molecular level to allowfacile ring opening and closing. Furthermore, in “ReversiblyColoring/Decoloring Reaction of Leuco Dye Controlled by Long-ChainMolecule,” by Horiguchi et. al, Thin Solid Films, Vol. 516 (2008), pp.2591-94, has shown that the reversible opening and closing of a similarleuco dye to that of the one or more leuco dyes that may be used in thepresent invention is regulated by the structural organization of theleuco dye and a long chain electron accepting compound. This structuralchange shows the occurrence of intercalation and deintercalation of theleuco dye in the reversible coloring process. It is believed that ininstances where the one or more masking colorants of the presentinvention are that of one or more leuco dyes, a similar mechanism is atleast partially responsible for the color effect that occurs with themigration of the one or more migratory activators into the receivinglayer. It has been shown that the cationic, open form of the leucodye(s) is not only sensitive to the polarity of solvents, but thatprotic solvents hydrogen bond to the initial colored state of the leucodye(s) and thus stabilize it. Therefore with the appropriate choice ofthe polymer(s) of the receiving layer, i.e. the use of a polymer(s) thatwill aid in the opening of the one or more leuco dyes through, forexample, its hydrogen bonding capacity or polarity, in combination withthat of the one or more deactivators, it is possible to cause andmaintain the one or more Leuco dyes in an initial colored state, priorto activation of the time validation indicator.

Once the time validation indicator is activated, i.e. placing at least aportion of the receiving layer in contact with at least a portion of theactivating layer, the predetermined time is initiated and the one ormore migratory activators begin to migrate into the receiving layercausing at least a portion of the one or more masking colorants toadvance to a final colorless state, by way of interfering/interactingwith at least the complex or hydrogen bonding of the one or more maskingcolorants in the initial colored state. Suitable migratory activatorsuseful in the present invention include, for example, neutralpolyoxygenated compounds such as, polyethylene glycols, polypropyleneglycols, polyglycol monoethers or diethers, as well as esters such as,for example, polypropylene glycol 400, polyethylene glycol 400,polyethylene glycol 1000, polyethylene glycol 200, polyethylene glycol600, polyethylene glycol dimethylether, or polyethylene glycolmonolauate, or nonionic surfactants such as, Triton X 100, orpolyethylene oxide-polypropylene oxide block polymers, such asPluronic®. Other useful compounds such as, amines, e.g. triethanolamine,dioctylamine, tert-octylamine, Tinuvin 292HP, Tinuvin 123,polyethyenimines, Primene JM-T-amine, etc., may be employed as one ormore migratory activators in the activating layer.

As stated above, the predetermined time period begins upon theactivation of the time validation indicator, i.e. when at least aportion of the receiving layer is placed in contact with at least aportion of the activating layer. In one aspect, according to the presentteachings, one or more adhesive materials may be incorporated into atleast the receiving layer, activating layer, or both, during formation,to bond together at least a portion of the receiving layer to at least aportion of the activating layer when placed in contact, as well as insome instances, to other additional layers of the time validationindicator. In another aspect, according to the present teachings, asillustrated in FIG. 4, the time validation indicator (10) may furthercomprise an adhesive layer (8), that comprises one or more adhesivematerials, such that the receiving layer (4) and the activating layer(6) are bonded together when at least a portion of the receiving layer(4) is placed in contact with at least a portion of the activating layer(6). In further instances, additional adhesive layers may be utilized toaid in bonding other layers of the time validation indicator with thatof the activating layer or receiving layer. The adhesive layer may beeither a preformed film of the one or more adhesive materials or in thealternative, prepared by coating the one or more adhesive materials ontoa release base, another layer of the time validation indicator, e.g.receiving layer or activating layer, or a base substrate. It should benoted that in instances where the adhesive layer is formed by coating alayer onto a release base, the release base is removed prior toactivation of the time validation indicator. The one or more adhesivematerials can be any suitable adhesive known in the art, e.g. pressuresensitive adhesives such as, natural or synthetic elastomers, acrylicadhesives, polymers of vinyl ethers or silicone gums, or those orsimilar to those described in “Pressure-Sensitive Adhesives,” by T. M.Goulding, Handbook of Adhesive Technology 2nd Edition, chapter 44(2003).

In a further aspect of the present teachings, as illustrated in FIG. 5,the time validation indicator (14) may further comprise a colorant layer(12) disposed onto at least a portion of the receiving layer (4). Inother aspects, the colorant layer may be disposed onto at least aportion of the activating layer. In either aspect, the colorant layercomprises one or more static colorants that are capable of beingvisually observed upon at least a portion of the one or more maskingcolorants of the receiving layer being partially or fully in the finalcolorless state. Alternatively, one or more static colorants may beincorporated into the activating layer, the receiving layer, or both. Inany of these instances, the one or more static colorants, e.g. dyes,pigments, inks, etc., provide for an increase in the visual contrastbetween the initial colored state and final colorless state of at leasta portion of the one or more masking colorants of the receiving layer,so that a more apparent or distinct visual color change of the receivinglayer may result. Thus, the one or more static colorants are generallychosen to display a visual color that substantially contrasts theinitial colored state of the one or more masking colorants of thereceiving layer. In some instances, it may be desired to incorporate oneor more static colorants into the activating layer or receiving layer orboth, as well as render another one or more static colorants as acolorant layer disposed onto either the receiving layer or activatinglayer. In this aspect, a wider color gamut may be produced by the timevalidation indicator to provide a visual contrasting color to that whichis produced by the one or more masking colorants being in the initialcolored state, thereby resulting in a greater distinct indication of thevisual color change of the receiving layer.

The colorant layer can be prepared by variety methods well known in theart. For example, coating a layer that is generally planar on a releasebase, another layer of the time validation indicator, e.g. theactivating layer or receiving layer, or a base substrate, the layerbeing prepared from a formulation. Such coatings can be deposited bypainting, printing, spraying, slot coating, dip coating, roller coating,bar coating, etc. It should be noted that in instances where thecolorant layer is formed by coating a layer onto a release base, therelease base is removed prior to activation of the time validationindicator. Alternatively, an effective colorant layer may be prepared byextrusion, injection molding, compression molding, calendaring,thermoforming, etc. In some instances, the colorant layer may alsocomprise one or more adhesive materials to aid in bonding the colorantlayer to other layers of the time validation indicator, e.g. receivinglayer or activating layer.

Referring now to FIG. 6, in a further aspect of the present teachings,the time validation indicator (18) may optionally comprise a timinglayer (16), disposed onto at least a portion of either the receivinglayer (4) or the activating layer (6), that further regulates or retardsthe rate of migration of the one or more migratory activators into thereceiving layer (4), to lengthen the predetermined time period, ifwarranted. Suitable materials for the timing layer may include, but arenot limited to, polyacrylics, polyurethanes, polycarbonates, polyesters,or fluorinated polymers, and are generally chosen based on the materialsability to slow migration of the one or more migratory activators fromthe activating layer to the receiving layer. In some instances, thetiming layer may also comprise one or more adhesive materials to aid inbonding the timing layer to other layers of the time validationindicator, e.g. receiving layer or activating layer. In other instances,the timing layer may also comprise one or more static colorants that arecapable of being visually observed upon at least a portion of the one ormore masking colorants of the receiving being partially or fully in thefinal colorless state. The timing layer can be prepared by coating alayer, by way of e.g. painting, printing, spraying, slot coating, dipcoating, roller coating, bar coating, etc., that is generally planar ona release base, another layer of the time validation indicator, e.g. theactivating layer or receiving layer, or a base substrate, the layerbeing prepared from a formulation. It should be noted that in instanceswhere the timing layer is formed by coating a layer onto a release base,the release base is removed prior to activation of the time validationindicator.

In another aspect of the present teachings, the time validationindicator may further comprise one or more base substrates. In someconstructions, at least a portion of the activating layer is disposedonto the one or more base substrates, whereas in other constructions atleast a portion of the receiving layer is disposed onto the one or morebase substrates. Furthermore in another construction, at least a portionof the activating layer may be disposed onto one of the one or more basesubstrates and at least a portion of the receiving layer may be disposedonto another one of the one or more base substrates. In some instances,one of the one or more base substrates may include an indicia areaindicia area that is capable of being visually observed upon at least aportion of the one or more masking colorants of the receiving layerbeing partially or fully in the final colorless state. For example, asshown in FIG. 7, the time validation indicator (22) includes one of theone or more base substrates (20) having an indicia area in the form ofthe word EXPIRED. FIG. 7A illustrates the time validation indicator (22)prior to at least a portion of the one or more masking colorants beingpartially or fully in the final colorless state, in which the indiciaarea is visually undetectable, whereas FIG. 7B illustrates the visualappearance of the indicia area of the time validation indicator (22)upon at least a portion the one or more masking colorants beingpartially or fully in the final colorless state. Suitable basesubstrates to be used in the present invention may include any materialsuited for printing or coating, e.g. Mylar film. In some instances, thesurface of an object may serve as the base substrate. In alternativeinstances, an indicia area may be applied onto any of the layers of thetime validation indicator. The indicia area may be printed or coatedonto a base substrate or a layer in the form of a message or othernumeric or alphabetic symbols, or shapes, etc., so that the indicia areamay become visually apparent following the visual color change of thereceiving layer. In a further aspect, the indicia area may be renderedinto the activating layer or receiving layer by way of incorporating oneor more static colorants in the form of a message or other numeric oralphabetic symbols, or shapes, etc., so that the indicia area may becomevisually apparent following the visual color change of the receivinglayer. The indicia area may be any color or more specifically, a colorthat enhances the contrast between the initial colored state and finalcolorless state of the one or more masking colorants of the receivinglayer.

In other aspects, the indicia area may in the form of a bar code whichbecomes altered following the migration of the one or more migratoryactivators into the receiving layer during the predetermined timeperiod. In such instance, upon the alteration of the bar code, aconventional bar code reading device can be used to read the altered barcode and indicate that the predetermined time period has elapsed.

According to the present teachings, the layers of the time validationindicator include one or more polymers that act as a binder. Examples ofpolymers that are useful in each layer of the present invention include,but are not limited to, acrylic polymers such as, Elvacite® (Lucite)2014 or NeoCryl® B818 (DSM), polyurethanes such as, MACE 107-295, orfluorinated polymers, such as FC 2230. It should be noted that the typeof polymer(s) used for each layer of the time validation indicator mayin some instances be the same, whereas in others, different. The choiceof polymer(s) for each layer will depend on solubility factorsassociated with the various materials in each layer. Any type ofpolymer(s) which allow the constituents of the activating layer tomigrate into the receiving layer is acceptable for use. Furthermore, interms of the receiving layer, the one or more polymers chosen to beincluded within such layer also aid the one or more deactivators incausing and maintaining the one or more masking colorants in the initialcolored state. This is because in some instances, the one or moredeactivators alone may not effectively cause and maintain the one ormore masking colorants in the initial colored state.

To further aid in the regulation of the predetermined time period, anyof the foregoing layers of the time validation indicator may furthercomprise one or more plasticizers. Plasticizers, most commonly phthalateesters, are additives used in polymers to impart improved flexibilityand durability. Plasticizers work by embedding themselves between thechains of polymer(s) thereby increasing the “free volume”, and thussubstantially lowering the glass transition temperature (Tg) of thepolymer(s) and making it softer. In other words, as a plasticizermigrates into the polymer(s) it disrupts the intermolecular forcesbetween polymer chains and thus allows for better movement betweenpolymer segments lowering the Tg which allows for easy migration ofother constituents, for example the one or more migratory activatorsinto that of the receiving layer.

Additional components that may be incorporated within any of theforegoing layers of the time validation indicator include, but are notlimited to, dispersant(s), thickener(s), wetting agent(s), defoamer(s),etc., that do not cause the one or more masking colorants of thereceiving layer to advance to a final colorless state before thepredetermined time period begins. Dispersants, wetting agents, ordefoamers may each be oligomeric, polymeric, or copolymeric materials orblends containing surface-active (surfactant) characteristic blocks,such as, for example, polyethers, polyols, or polyacids. Examples ofdispersants include acrylic acid-acrylamide polymers, or salts of aminefunctional compound and acid, hydroxyfunctional carboxylic acid esterswith pigment affinity groups, and combinations thereof, for exampleDISPERBYK®-180, DISPERBYK®-181, DISPERBYK®-108, all from BYK-Chemie, andTEGO® Dispers 710 from Degussa GmbH. Wetting agents are suitablesurfactant materials, and may be selected from among polyether siloxanecopolymers, for example, TEGO® Wet 270, non-ionic organic surfactants,for example, TEGO® Wet 500, and combinations thereof. Defoamers may beorganic modified polysiloxanes, for example, TEGO® Airex 900.

The timing period between placing the layers of the time validationindicator in contact with one another and the visual color change of thereceiving layer depends on a series of variables that are controllableand allow for the manipulation of the time validation indicator, inaccordance with the present teachings, for various predetermined timeperiods. Since the visual color change of the receiving layer depends onthe migration kinetics of the one or more migratory activators, anyparameter that affects such kinetics will, as a result, also affect thetiming period and therefore, may be utilized in varying the timingperiod of the present invention to match the predetermined time perioddesired. Examples of such parameters include, but are not limited to,the concentration of the one or more deactivators, the concentration ofthe one or more migratory activators, and/or the types of the one ormore migratory activators, all described in more detail below. It shouldbe noted that the graphs of FIGS. 8-12 were based on a mathematicalmodel derived from the optical density changes over time, i.e. therelation between density and time of contact (activation), of variousexamples of the time validation indicator of the present teachings. Theoptical density changes were measured using a MacBeth Spectrolino. Thisrelationship provided a mathematical regression which was then used fornormalization and extrapolation to create the graphs illustrated inFIGS. 8-12.

By way of example, FIG. 8 depicts the affect varying concentrations ofthe one or more deactivators in the receiving layer have on the timingperiod of the present invention. In this example, three differentreceiving layers were provided that included malonic acid as thedeactivator. The first receiving layer comprised a malonic acidconcentration of 0.25%, the second receiving layer comprised a malonicacid concentration of 0.50%, and the third receiving layer comprisedlayer a malonic acid concentration 1.00%. In addition, each of the threedifferent receiving layers also included 0.5% Black Dye 400 as themasking colorant and 20% FC-2230 fluoroelastomer. Three commonactivating layers were provided each comprising 20% polyethylene glycoldimethylether (PEGDME) as the migratory activator with 20% plasticizer,P-670, in 28% Elvacite® 2014. Each receiving layer was placed in contactwith a respective activating layer and then monitored for changes inoptical density over time using a MacBeth Spectrolino. As shown in FIG.8, it was determined that by increasing the concentration of the one ormore deactivators, from 0.25% to 1.00%, it took approximately 240 hourslonger for the time validation indicator of the present teachings toreach the same optical density with 1.00% concentration of thedeactivator versus 0.25% concentration of the deactivator. Furthermore,the type of one or more deactivators, e.g. maleic acid, malic acid,fumaric acid, terephthalic acid, propyl gallate, etc., can also furtheraffect the migration kinetics of the one or more migratory activatorsinto that of the receiving layer of the time validation indicator of thepresent teachings.

In another example, now referring to FIG. 9, the concentration of theone or more migratory activators may also influence the timing period ofthe present invention. In this example, three different activatinglayers were provided that included PEDGME as the migratory activator.The first activating layer comprised a PEDGME concentration of 2%, thesecond activating layer comprised a PEDGME concentration of 10%, and thethird activating layer comprised a PEDGME concentration of 20%. Inaddition, each of the three different activating layers also included10% P-670 in 28% Elvacite® 2014. Three common receiving layers were alsoprovided each comprising 0.5% Black Dye 400 as the masking colorant and1% malonic acid as the deactivator in 20% FC-2230 fluoroelastomer. Eachactivating layer was placed in contact with its respective receivinglayer and then monitored for changes in optical density over time usinga MacBeth Spectrolino. As seen in FIG. 9, increases in PEGDMEconcentration, i.e. from 2% to 10% to 20%, led to a decreased timingperiod, as expected, since higher concentration levels of the one ormore migratory activators will increase the rate the one or more maskingcolorants advance from the initial colored state to the final colorlessstate. In addition to varying the concentration of the one or moremigratory activators, the types of the one or more migratory activatorsutilized in the activating layer also affects the timing period of thepresent invention, as illustrated in FIG. 10. Now referring to FIG. 10,six common receiving layers were provided each one having the samecomposition as the receiving layers in FIG. 9 and six differentactivating layers were provided each having a different type ofmigratory activator at 2% concentration with 10% P-670 in 28% Elvacite®2014. Each activating layer was placed in contact with its respectivereceiving layer and then monitored for changes in optical density overtime using a MacBeth Spectrolino. As depicted in FIG. 10 the type ofmigratory activator(s) used within the activating layer maysubstantially alter the timing period of the time validation indicatorof the present teachings.

In addition to the above mentioned parameters, the glass transitiontemperature (Tg) and/or the polarity of the polymer(s) of the activatinglayer and/or the receiving layer, and/or the thickness of the layersincluded in the time validation indicator can also affect the timingperiod. In instances where the time validation indicator also includesan adhesive layer disposed between the receiving layer and activatinglayer, the composition of the adhesive layer may also affect themigration kinetics of the one or more migratory activators, therebyaffecting the timing period. In other instances where the timevalidation indicator also comprises a timing layer disposed between thereceiving layer and the activation layer, the polymer(s), as well as thethickness of such timing layer, may also affect the migration kineticsof the one or more migratory activators. Furthermore, it has also beenfound that the concentration of the one or more masking colorants mayalso influence the migration kinetics of the one or more migratoryactivators. For example, in the instance where black leuco dye(s) arethe one or more masking colorants, it was found that not only thethickness of the receiving layer, but the concentration of the blackleuco dye(s) can affect the amount of time it takes for such dye(s) togo from an initial colored state to that of a final colorless state.Therefore, the higher the concentration of the one or more maskingcolorants present in the receiving layer, the longer the timing period,which is also similar to the affect the concentration of the one or moredeactivators may have on the timing period.

In any aspect of the time validation indicator of the present teachings,the final migration kinetics of the one or more migratory activators canbe managed by the use of one or more plasticizers incorporated into atleast the activating layer as shown by way of example in FIG. 11. Inthis example three different activating layers were provided each having2% PEGDME in 28% Elvacite® 2014, as well as plasticizer, P-670. Theplasticizer concentration of the first activating layer was 5%, theplasticizer concentration of the second activating layer was 10%, andthe plasticizer concentration in the third activating layer was 20%.Three common receiving layers were also provided, each comprising 0.5%Black Dye 400 with 1% malonic acid in 20% FC-2230 fluoroelastomer. Eachactivating layer was placed in contact with its respective receivinglayer and then monitored for changes in optical density over time usinga MacBeth Spectrolino. As shown in FIG. 11, a change in timing periodresults due to the concentration level of the P-670 present in theactivating layer, i.e. the higher concentrations of P-670 can lead tofaster migration kinetics and shorter timing periods of the presentinvention, since the one or more plasticizers not only lowers the Tg ofthe FC-2230 polymer within the receiving layer, but also allows for easeof migration of the migratory activator PEGDME. In addition to theactivating layer, in some instances, the receiving layer may alsocomprise one or more plasticizers, as illustrated by way of example inFIG. 12. Now referring to FIG. 12, two different receiving layers wereprovided, each comprising 0.5% Black Dye 400 with 1% malonic acid in 20%FC-2230 fluoroelastomer. One of the receiving layers also comprised aplasticizer, P-670, at 5% concentration. In addition, two commonactivating layers were also provided, each having 2% PEGDME with 10%plasticizer, P-670, in 28% Elvacite® 2014. Each receiving layer wasplaced in contact with its respective activating layer and thenmonitored for changes in optical density over time using a MacBethSpectrolino. As seen in FIG. 12, in the instances where both theactivating layer and receiving layer comprise one or more plasticizers,the timing period of the present invention can be substantiallyshortened due to the one or more plasticizers of the receiving layeraiding in the migration kinetics of the one or more migratoryactivators. Thus, various combinations of plasticizer concentrations inthe activating layer and/or the receiving layer can be used to furtheradapt the timing period, such that the time validation indicator of thepresent teachings can be used to determine the expiration of a widevariety of time intervals. Optionally, one or more plasticizers may alsobe incorporated into any additional layers that may be included withinthe time validation indicator of the present teachings to further aid inthe migration kinetics of the one or more migratory activators.

The time validation indicator, according to the present teachings, maybe fabricated by any method well known to those skilled in the art. Onesuch method may include forming a receiving layer, forming an activatinglayer, and placing at least a portion of the receiving layer in contactwith at least a portion of the activating layer to initiate thepredetermined time period and the migration of the one or more migratoryactivators into the receiving layer. A variety of methods can be used toform an effective receiving layer and activating layer. Such methods mayinclude coating a layer, by way of e.g. painting, printing, spraying,slot coating, dip coating, roller coating, bar coating, etc., that isgenerally planar on a release base, a surface of an object, anotherlayer of the time validation indicator, or a base substrate, the layerbeing prepared from a formulation. It should be noted that in instanceswhere the receiving layer or activating layer is formed by coating alayer onto a release base, the release base is removed prior toactivation of the time validation indicator. Alternatively, an effectivereceiving layer or activating layer may be prepared by extrusion,injection molding, compression molding, calendaring, thermoforming, etc.The placing of at least a portion of the receiving layer in contact withat least a portion of the activating layer may include either directcontact, i.e. no additional layers are disposed between the activatinglayer and receiving layer, or indirect contact, i.e. one or moreadditional layers are disposed between the activating layer and thereceiving layer, e.g. an adhesive layer and/or a timing layer. In someinstances, the placing of at least a portion of the receiving layer incontact with at least a portion of the activating may be done withoutthe use of an adhesive means, while in other instances adhesive meansmay be utilized. The adhesive means, if used, bonds together at least aportion of the receiving layer to at least a portion of the activatinglayer when placed in contact. The adhesive means may be applied byrendering an adhesive layer onto at least a portion of the receivinglayer and/or the activating layer, or in the alternative byincorporating one or more adhesive materials into the receiving layerand/or the activating layer during formation. In another aspect, themethod may further include rendering a colorant layer disposed onto atleast a portion of either the receiving layer or the activating layer.In other instances, the method may also include applying a timing layerdisposed onto at least a portion of the receiving layer or theactivating layer. In further aspects, the method may optionally includerendering one or more base substrates, in which at least a portion of atleast the activating layer or the receiving layer is disposed onto theone or more base substrates. It should be noted that additional adhesivemeans may also be utilized to bond other layers, e.g. colorant layerand/or timing layer, if present, to that of the activating layer,receiving layer, or a base substrate.

The time validation indicators, according to the present teachings, areapplicable to various instances that warrant an indication of the elapseof a predetermined time period. For example, the expiration of ashelf-life of an object, general inventory management, etc. One methodfor indicating a predetermined time period has elapsed may includeproviding a time validation indicator, in accordance with the presentteachings, placing at least a portion of the receiving layer in contactwith at least a portion of the activating layer to initiate thepredetermined time period and the migration of the one or more migratoryactivators into the receiving layer, and detecting the visual colorchange of the receiving layer that indicates the predetermined timeperiod has elapsed. In a further aspect, the method may also includeapplying the time validation indicator to at least a portion of anobject. The adaptability of the layers of the time validation indicatoraccording to the present teachings, enables the time validationindicator to be utilized for a host of different time intervals andtherefore instances in which visual indication of the elapse of apredetermined time period is sought.

EXEMPLIFICATIONS

The present teachings, having been generally described, will be morereadily understood by reference to the following examples, which areincluded merely for the purposes of illustration of certain aspects andembodiments of the present teachings, and are not intended to limit thescope of these teachings. It should be noted that, unless otherwisespecified, the weight % values mentioned in the below examples aremeasured relative to a solid state.

Example 1 Preparation of a Time Validation Indicator with aPredetermined Time Period of Approximately 144 Hours

Receiving Layer:

-   -   To 25.0 g of a magnetically stirred solution of 20% FC-2230        fluoroelastomer (3M, Dyneon) in ethyl acetate is added 0.5%        (0.025 g) Black Dye 400 from Yamada Chemical Co., 1% (0.050 g)        Malonic Acid from Aldrich Chemical and 5% Plasthall P-670 from        Hallstar (1.39 g based on total weight of components including        the Plasthall). This formulation was stirred at room temperature        for 30 minutes until fully dissolved and then sonicated        (Branson 2200) for 15 minutes at room temperature to remove air        bubbles and to insure a uniform mixture. This formulation was        then coated on a base substrate, Mylar film of 10 mils, using a        20 mil Bird bar and dried at 40° C. for 4 hours and then at        80° C. for 14 hours to yield a receiving layer.

Activating Layer:

-   -   To 25.0 g of a magnetically stirred solution of 28% Elvacite®        2014 (Lucite International/Chempoint) in toluene is added 20%        (0.35 g) polyethylene glycol dimethylether (Aldrich), and 20%        Plasthall-P670 (6.63 g based on total weight of components        including the Plasthall). This formulation was stirred at room        temperature for 30 minutes until fully dissolved and then        sonicated (Branson 2200) for 15 minutes at room temperature to        remove air bubbles and to insure a uniform mixture. This        formulation was then coated on a base substrate, Mylar film of        10 mils, using a 20 mil Bird bar and dried at 40° C. for 4 hours        and then at 80° C. for 14 hours to yield an activating layer.

Adhesive Layer:

-   -   Prepared by coating #9026 transfer adhesive (3M) onto the        activating layer to yield an adhesive layer.        The receiving layer was then cold laminated to the adhesive        layer, thereby placing at least a portion of the receiving layer        in contact with at least a portion of the activating layer to        begin the predetermined time period and initiate the migration        of the one or more migratory activators into the receiving layer        causing at least a portion of the one or more masking colorants        to advance to a final colorless state.

Example 2 Preparation of a Time Validation Indicator with aPredetermined Time Period of Approximately 4300 Hours

Receiving Layer:

-   -   Prepared as in Example 1.

Timing Layer:

-   -   To 25.0 g of a magnetically stirred solution of 28% Elvacite®        2014 is added 5% Plasthall-P670 (1.39 g based on total weight of        components including the Plasthall). This formulation was        stirred at room temperature for 30 minutes until fully dissolved        and then sonicated (Branson 2200) for 15 minutes at room        temperature to remove air bubbles and to insure a uniform        mixture. This formulation was then coated on a release base        using a 20 mil Bird bar and dried in an oven at 40° C. for 4        hours and then at 80° C. for 14 hours to yield a timing layer.        The timing layer was then heat laminated to the receiving layer.

Activation Layer:

-   -   To 25.0 g of a magnetically stirred solution of 28% Elvacite®        2014 in toluene is added 20% (0.35 g) polyethylene glycol        dimethylether, and 10% Plasthall-P670 (2.95 g based on total        weight of components including the Plasthall). This formulation        was stirred at room temperature for 30 minutes until fully        dissolved and then sonicated (Branson 2200) for 15 minutes at        room temperature to remove air bubbles and to insure a uniform        mixture. This formulation was then coated on a base substrate,        Mylar film of 10 mils, using a 20 mil Bird bar and dried at        40° C. for 4 hours and then at 80° C. for 14 hours to yield an        activating layer.

Adhesive Layer:

-   -   Prepared by coating #9026 transfer adhesive (3M) onto the        activating layer to yield an adhesive layer.        The timing layer was then cold laminated to the adhesive layer,        thereby placing at least a portion of the receiving layer in        contact with at least a portion of the activating layer to begin        the predetermined time period and initiate the migration of the        one or more migratory activators into the receiving layer        causing at least a portion of the one or more masking colorants        to advance to a final colorless state.

Example 3 Preparation of a Time Validation Indicator with aPredetermined Time Period of Approximately 330 Hours

Receiving Layer:

-   -   To 25.0 g of a magnetically stirred solution of 20% FC-2230        fluoroelastomer in ethyl acetate is added 1.0% (0.050 g) Black        Dye 400, and 1% (0.050 g) malonic acid. This formulation was        stirred at room temperature for 30 minutes until fully dissolved        and then sonicated (Branson 2200) for 15 minutes at room        temperature to remove air bubbles and to insure a uniform        mixture. This formulation was then coated onto a base substrate,        Mylar film of 2 mils, using a 20 mil Bird bar and dried at        40° C. for 4 hours and then at 80° C. for 14 hours to yield a        receiving layer.

Timing Layer:

-   -   To 25.0 g of a magnetically stirred solution of 28% Elvacite®        2014 is added 5% Plasthall-P670 (1.39 g based on total weight of        components including the Plasthall). This formulation was        stirred at room temperature for 30 minutes until fully dissolved        and then sonicated (Branson 2200) for 15 minutes at room        temperature to remove air bubbles and to insure a uniform        mixture. This formulation was then coated on a release base        using a 20 mil Bird bar and dried in an oven at 40° C. for 4        hours and then at 80° C. for 14 hours to yield a timing layer.

Colorant Layer:

-   -   To 25.0 g of a magnetically stirred solution of 28% Elvacite®        2014 in toluene is added 10% (0.70 g) of Red BSR-RD213        (Brilliant). This formulation was stirred at room temperature        for 30 minutes until fully dissolved and then sonicated        (Branson 2200) for 15 minutes at room temperature to remove air        bubbles and to insure a uniform mixture. This formulation was        then coated onto a base substrate, Mylar film of 2 mils, using a        20 mil Bird bar and dried at 40° C. for 4 hours and then at        80° C. for 14 hours to yield a colorant layer.

Adhesive Layer 1:

-   -   Prepared by coating #9026 transfer adhesive (3M) onto the        colorant layer to yield an adhesive layer.

Activating Layer:

-   -   To 25.0 g of a magnetically stirred solution of 28% Elvacite®        2014 in toluene is added 10% (0.175 g) polyethylene glycol        dimethylether, and 20% Plasthall-P670 (6.30 g based on total        weight of components including the Plasthall). This formulation        was stirred at room temperature for 30 minutes until fully        dissolved and then sonicated (Branson 2200) for 15 minutes at        room temperature to remove air bubbles and to insure a uniform        mixture. This formulation was then coated on a release base,        Mylar film of 2 mils, using a 20 mil Bird bar and dried at        40° C. for 4 hours and then at 80° C. for 14 hours to yield an        activating layer.

Adhesive Layer 2:

-   -   Prepared by coating #9026 transfer adhesive (3M) onto the        activating layer to yield an adhesive layer.        The adhesive layer 1 was cold laminated to one side of the        receiving layer and the timing layer was cold laminated to the        opposing side of the receiving layer. The adhesive layer 2 was        then cold laminated to the timing layer, thereby placing at        least a portion of the receiving layer in contact with at least        a portion of the activating layer to begin the predetermined        time period and initiate the migration of the one or more        migratory activators into the receiving layer causing at least a        portion of the one or more masking colorants to advance to a        final colorless state.

For the purposes of describing and defining the present teachings, it isnoted that the term “substantially” is utilized herein to represent theinherent degree of uncertainty that may be attributed to anyquantitative comparison, value, measurement or other representation. Theterm “substantially” is also utilized herein to present the degree bywhich a quantitative representation may vary from a stated referencewithout resulting in a change in the basic function of the subjectmatter at issue.

Although the teachings have been described with respect to variousembodiments, it should be realized that these teachings are also capableof a wide variety of further and other embodiments within the spirit andscope of the appended disclosure.

What is claimed is:
 1. A time validation indicator, said time validationindicator comprising: a receiving layer that comprises: (i) one or moremasking colorants, wherein the masking colorant is a leuco dye that iscapable of reversibly forming a colored carbonium ion species; and (ii)one or more deactivators comprising an electron accepting compound and afluoropolymer, wherein the one or more deactivators cause and maintainsaid one or more masking colorants in an initial colored state; and anactivating layer that comprises one or more migratory activators thatmigrate into said receiving layer upon at least a portion of saidreceiving layer being placed in contact with at least a portion of saidactivating layer to initiate a predetermined time period; wherein themigration of said one or more migratory activators into said receivinglayer causes at least a portion of said one or more masking colorants toadvance to a final colorless state resulting in a visual color change ofsaid receiving layer that indicates the predetermined time period haselapsed.
 2. The time validation indicator of claim 1, wherein said oneor more migratory activators are one or more polyoxygenated compounds.3. The time validation indicator of claim 1, wherein at least one ofsaid receiving layer or said activating layer further comprises one ormore plasticizers that aid in the migration of said one or moremigratory activators into said receiving layer.
 4. The time validationindicator of claim 1, wherein at least one of said receiving layer orsaid activating layer further comprises at least one of one or moredispersants, one or more thickeners, one or more wetting agents, or oneor more defoamers.
 5. The time validation indicator of claim 1, whereinat least one of said receiving layer or said activating layer furthercomprises one or more adhesive materials that bond together at least aportion of said receiving layer to at least a portion of said activatinglayer when placed in contact.
 6. The time validation indicator of claim1, furthering comprising an adhesive layer that bonds together at leasta portion of said receiving layer to at least a portion of saidactivating layer when placed in contact.
 7. The time validationindicator of claim 1, wherein at least one of said activating layer orsaid receiving layer further comprises one or more static colorants thatare capable of being visually observed upon at least a portion of saidone or more masking colorants of said receiving layer being partially orfully in said final colorless state.
 8. The time validation indicator ofclaim 1, further comprising a colorant layer that comprises one or morestatic colorants that are capable of being visually observed upon atleast a portion of said one or more masking colorants of said receivinglayer being partially or fully in said final colorless state.
 9. Thetime validation indicator of claim 1, further comprising a timing layerthat at least partially retards the rate of migration of said one ormore migratory activators into said receiving layer.
 10. The timevalidation indicator of claim 1, further comprising one or more basesubstrates.
 11. The time validation indicator of claim 10, wherein oneof said one or more base substrates comprises an indicia area that iscapable of being visually observed upon at least a portion of said oneor more masking colorants of said receiving layer being partially orfully in said final colorless state.
 12. The time validation indicatorof claim 1, wherein the fluoropolymer is a fluoroelastomer.
 13. A methodfor fabricating a time validation indicator, said method comprising:forming a receiving layer that comprises; (i) one or more maskingcolorants, wherein the masking colorant is a leuco dye that is capableof reversibly forming a colored carbonium ion species; and (ii) one ormore deactivators comprising an electron accepting compound and afluoropolymer, wherein the one or more deactivators cause and maintainsaid one or more masking colorants to be in an initial colored state;forming an activating layer that comprises one or more migratoryactivators that migrate into said receiving layer upon at least aportion of said receiving layer being placed in contact with at least aportion of said activating layer to initiate a predetermined timeperiod; and placing at least a portion of said receiving layer incontact with at least a portion of said activating layer to initiate thepredetermined time period and the migration of said one or moremigratory activators into said receiving layer, wherein the migration ofsaid one or more migratory activators into said receiving layer causesat least a portion of said one or more masking colorants to advance to afinal colorless state resulting in a visual color change of saidreceiving layer that indicates the predetermined time period haselapsed.
 14. The method of claim 13, further comprising applying anadhesive means that bonds together at least a portion of said receivinglayer to at least a portion of said activating layer when placed incontact.
 15. The method of claim 14, wherein applying said adhesivemeans comprises rendering an adhesive layer onto at least a portion ofat least one of said receiving layer or said activating layer.
 16. Themethod of claim 14, wherein applying said adhesive means comprisesincorporating one or more adhesive materials into at least one of saidreceiving layer or said activating layer.
 17. The method of claim 13,wherein at least one of said activating layer or said receiving layerfurther comprises one or more static colorants that are capable of beingvisually observed upon at least a portion of said one or more maskingcolorants of said receiving layer being partially or fully in said finalcolorless state.
 18. The method of claim 13, further comprisingrendering a colorant layer disposed onto at least a portion of saidactivating layer, wherein said colorant layer comprises one or morestatic colorants that are capable of being visually observed upon atleast a portion of said one or more masking colorants of said receivinglayer being partially or fully in said final colorless state.
 19. Themethod of claim 13, further comprising rendering a colorant layerdisposed onto at least a portion of said receiving layer, wherein saidcolorant layer comprises one or more static colorants that are capableof being visually observed upon at least a portion of said one or moremasking colorants of said receiving layer being partially or fully insaid final colorless state.
 20. The method of claim 13, furthercomprising applying a timing layer disposed onto at least a portion ofsaid activating layer, wherein said timing layer at least partiallyretards the rate of migration of said one or more migratory activatorsinto said receiving layer.
 21. The method of claim 13, furthercomprising applying a timing layer disposed onto at least a portion ofsaid receiving layer, wherein said timing layer at least partiallyretards the rate of migration of said one or more migratory activatorsinto said receiving layer.
 22. The method of claim 13, furthercomprising rendering one or more base substrates, wherein at least aportion of at least one of said activating layer or said receiving layeris disposed onto said one or more base substrates.
 23. The method ofclaim 22, wherein one of said one or more base substrates comprises anindicia area that is capable of being visually observed upon at least aportion of said one or more masking colorants of said receiving layerbeing partially or fully in said final colorless state.
 24. The methodof claim 13, wherein the fluoropolymer is a fluoroelastomer.
 25. Amethod for indicating a predetermined time period has elapsed, saidmethod comprising: providing a time validation indicator that comprises;a receiving layer comprising; (i) one or more masking colorants, whereinthe masking colorant is a leuco dye that is capable of reversiblyforming a colored carbonium ion species; and (ii) one or moredeactivators comprising an electron accepting compound and afluoropolymer, wherein the one or more deactivators cause and maintainsaid one or more masking colorants to be in an initial colored state;and an activating layer comprising one or more migratory activators thatmigrate into said receiving layer to cause at least a portion of saidone or more masking colorants to advance to a final colorless state thatresults in a visual color change of said receiving layer; placing atleast a portion of said receiving layer in contact with at least aportion of said activating layer to initiate the predetermined timeperiod and the migration of said one or more migratory activators intosaid receiving layer, and detecting said visual color change of saidreceiving layer that indicates the predetermined time period haselapsed.
 26. The method of claim 25, further comprising applying saidtime validation indicator to at least a portion of a surface of anobject.
 27. The method of claim 25, wherein said time validationindicator further comprises an adhesive means that bonds together atleast a portion of said receiving layer with at least a portion of saidactivating layer when placed in contact.
 28. The method of claim 25,wherein at least one of said activating layer or said receiving layerfurther comprises one or more static colorants that are capable of beingvisually observed upon at least a portion of said one or more maskingcolorants of said receiving layer being partially or fully in said finalcolorless state.
 29. The method of claim 25, wherein said timevalidation indicator further comprises a colorant layer having one ormore static colorants that are capable of being visually observed uponat least a portion of said one or more masking colorants of saidreceiving layer being partially or fully in said final colorless state.30. The method of claim 25, wherein said time validation indicatorfurther comprises a timing layer that at least partially retards therate of migration of said one or more migratory activators into saidreceiving layer.
 31. The method of claim 25, wherein said timevalidation indicator further comprises one or more base substrates. 32.The method of claim 31, wherein one of said one or more base substratescomprises an indicia area that is capable of being visually observedupon at least a portion of said one or more masking colorants of saidreceiving layer being partially or fully in said final colorless state.33. The method of claim 25, wherein the fluoropolymer is afluoroelastomer.